000
AXPZ20 KNHC 160303
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC TUE APR 16 2013

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...             
THE MONSOON TROUGH AXIS IS ANALYZED FROM 08N79W TO 07N90W TO 
06N98W. ITCZ AXIS EXTENDS FROM 07N98W TO 05N110W TO 07N120W TO 
04N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 
120 NM S OF THE AXIS BETWEEN 117W AND 120W...AND 60 NM OF THE 
AXIS OF THE AXIS BETWEEN 112W AND 114W. SCATTERED MODERATE 
CONVECTION WITHIN 120 NM S OF THE AXIS BETWEEN 108W AND 112W. 

...DISCUSSION...                                                
A MID/UPPER TROUGH EXTENDS FROM NEAR 09N102W NWWD TO 20N108W TO  
THE CENTRAL BAJA CALIFORNIA PENINSULA. NW UPPER FLOW W OF THE 
TROUGH DIVERGES AROUND THE TROUGH E OF ABOUT 113W WHICH 
CONTINUES TO ENHANCE THE VERTICAL MOTION FROM THE ITCZ TO 10N 
AND BETWEEN 108W AND 112W WHERE DEEP ATMOSPHERIC MOISTURE AND 
INSTABILITY IS EVIDENT. THIS IS LEADING TO CONVECTION AS 
DESCRIBED ABOVE.  

UPPER LEVEL DIFFLUENCE ASSOCIATED WITH A HIGHLY AMPLIFIED RIDGE 
THAT STRETCHES FROM AN UPPER ANTICYCLONE OVER THE S CENTRAL 
CARIBBEAN SEA WNW ACROSS CENTRAL AMERICA AND FAR SE MEXICO IS  
CONTRIBUTING TO LIFT NEAR AN AREA OF POOLED LOW TO MID-LEVEL 
MOISTURE ALONG AND WITHIN 180 NM N OF THE MONSOON TROUGH BETWEEN 
90W AND 94W WHERE EARLY DEEP CONVECTION HAS RECENTLY WEAKENED 
TO WIDELY SCATTERED SHOWERS AND TSTMS. DEBRIS BLOWOFF 
MOISTURE...IN THE FORM OF SCATTERED TO BROKEN CIRRUS CLOUDS 
RELATED TO THIS CONVECTION...IS BEING CHANNELED NWD AROUND THE 
WRN PERIPHERY OF THE RIDGE TO ACROSS SE MEXICO...AND FROM 
HONDURAS SWD TO PANAMA.

TO THE NE OF THE DISCUSSION AREA OVER THE WRN CONUS REGION...A 
MEAN UPPER TROUGH STRETCHES SWD TO NRN BAJA CALIFORNIA. NRN 
STREAM ENERGY...IN THE FORM OF SHORTWAVE TROUGH IS ENTERING THE 
WRN PERIPHERY OF THE TROUGH OVER THE FAR ERN OF THE E PACIFIC N 
OF THE DISCUSSION AREA. THIS WILL HELP INTENSIFY THE TROUGH 
THROUGH WED...WHILE ALSO HELPING TO AMPLIFY THE RIDGE OVER THE 
FAR WRN PART OF THE AREA AS IT SHIFTS EWD. AN UPPER LOW NOTED ON 
SATELLITE WATER VAPOR OVER THE FAR NW PORTION NEAR 28N139W WILL 
SLOWLY MOVE NE INTO THE FAR NW CORNER OF THE AREA THROUGH TUE. 
HOWEVER...A RATHER DRY AND STABLE SURROUNDING ENVIRONMENT WILL 
INHIBIT THE DEVELOPMENT OF ANY CONVECTION WITH THIS LOW. A DEEP 
LAYER TROUGH W OF THE AREA NEAR 148W IS ATTENDANT BY A JET 
STREAM BRANCH THAT ENTERS THE DISCUSSION AREA THROUGH 
21N140W...AND REACHES TO NEAR 24N130W AND FURTHER E TO 23N124W 
BEFORE IT BECOMES ILL-DEFINED. BROKEN TO OVERCAST CIRRUS 
CLOUDS...SOME DUE TO CONVECTION BLOWOFF FROM THE WRN PORTION OF 
THE ITCZ...ARE ALONG AND S OF THIS JET STREAM BRANCH. THESE 
CLOUDS ARE STREAMING E AND NEWD INTO THE FAR WRN PART OF THE 
AREA S OF 22N AND W OF 120W. 

AT THE SURFACE...A RIDGE EXTENDS SEWD INTO THE AREA THROUGH  
32N134W AND TO NEAR 22N118W. HIGH PRES COVERS THE AREA N OF 16N 
AND W OF 123W. THE ASCAT PASS FROM 1810 UTC MON AFTERNOON 
REVEALED MAINLY LIGHT TO MODERATE NE TRADE WINDS TO THE W OF THE 
RIDGE AXIS. THE ASCAT PASS ALSO REVEALED N TO NE 20 KT WINDS N 
OF 28N AND BETWEEN 120W AND 129W. THESE WINDS ARE S OF A TIGHT 
PRES GRADIENT JUST N OF THE AREA WHERE GALE FORCE WINDS ARE 
FORECAST TO AGAIN DEVELOP VERY SOON. N SWELLS ARE PROPAGATING S 
FROM THIS REGION INTO NE FORECAST WATERS...WITH SEAS OF 8-11 FT 
N OF 27N AND BETWEEN 118W AND 131W. 

AN OSCAT PASS FROM 1944 UTC MON CLEARLY DEPICTED LOW PRES ALONG 
THE ITCZ NEAR 07N116W. THE WIND VECTORS REVEALED A RELATIVELY 
WELL DEFINED CYCLONIC INFLOW INTO THE LOW. LATEST SATELLITE 
IMAGERY SHOWS SCATTERED MODERATE/ISOLATED STRONG CONVECTION 
WITHIN 60 NM OF THE LOW...AND ALSO WITHIN 45 NM OF A LINE FROM 
07N114W TO 09N115W TO 10N117W. TOTAL PRECIPITABLE WATER (TPW) 
MOISTURE COMPOSITE ANIMATION INDICATES THAT THE LOW IS WITHIN AN 
AREA OF CONCENTRATED DEEP ATMOSPHERIC MOISTURE. THE LOW IS JUST 
TO THE E OF AN UPPER LEVEL ANTICYCLONE AT 08N119W. GLOBAL MODELS 
TEND TO SUGGEST THAT THE LOW WILL MOVE IN A WESTWARD MOTION OVER 
THE NEXT 48 HRS...BUT SHOULD REMAIN WEAK IN INTENSITY AS IT 
ENHANCES CONVECTION SOME ALONG AND NEAR THE ITCZ.

MODELS FORECAST THAT THE SURFACE RIDGE WILL STRENGTHEN OVER THE 
NEXT 48 HRS WITH THE SUPPORT OF A PARENT STRONG HIGH CENTER N OF 
THE AREA THAT MOVES SWD TOWARDS THE N CENTRAL WATERS. A 
WEAKENING COLD FRONT APPROACHING FAR NRN BAJA CALIFORNIA WILL 
INTO A TROUGH TUE MORNING AS IT SHIFTS NE OF THE AREA WITH THE 
STRENGTHENING OF THE RIDGE. THE PRES GRADIENT WILL TIGHTEN 
THROUGH THE GULF OF CALIFORNIA BY LATE WED INDUCING NW WINDS OF 
20 TO 25 KT THROUGH THE NRN GULF OF CALIFORNIA. MEANWHILE...A 
TIGHT PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES OVER THE 
INTER-MOUNTAIN U.S. IS EXPECTED TO KEEP GALE FORCE WINDS ALONG 
THE CALIFORNIA COAST THROUGH TUE BEFORE WEAKENING. THE 
ASSOCIATED NORTHERLY SWELLS WILL CONTINUE TO PROPAGATE INTO NE 
FORECAST WATERS...WITH SEAS EXPECTED TO BUILD AS HIGH AS 11 FT N 
OF ABOUT 28N THROUGH TUE.

$$
AGUIRRE